A bistable pitch propeller is able to switch between a first pitch angle and a second pitch angle where the terms “pitch position” and “blade position” are sometimes used in place of the term “pitch angle”. Some other types of propellers with multiple and/or adjustable pitch angles use active control mechanisms (e.g., hydraulic systems) to adjust the pitch angle. However, active control mechanisms are expensive and/or heavy, which makes such propellers unattractive for some applications.
In contrast, a bistable pitch propeller passively switches between two pitch angles by rotating the bistable pitch propeller faster or slower using a propulsion motor. Current bistable pitch propellers include mechanisms which change pitch angles when the bistable pitch propeller rotates at certain rotations per minute (RPM). However, having the switching mechanism be sensitive to RPMs (e.g., as opposed to some other metric or unit) is undesirable because the bistable pitch propeller needs to stay out of the RPM “switching range” in order to hold the current pitch angle. Conversely, to change the pitch angle, the bistable pitch propeller may need to be sped up or slowed down in order to be in the RPM “switching range.” This may interrupt natural or organic flying of the aircraft. New mechanisms which permit a bistable pitch propeller to switch pitch angles in a more desirable and/or organic manner would be desirable.